Abstract-Elucidation of Chiral-symmetry Breaking in a Racemic Polymer System with Terahertz Vibrational Spectroscopy and Crystal Orbital Density Functional Theory

Feng Zhang, Houng-Wei Wang, Keisuke Tominaga, Michitoshi Hayashi, Sunglin Lee, and Takashi Nishino

J. Phys. Chem. Lett., Just Accepted Manuscript

DOI: 10.1021/acs.jpclett.6b02213

Publication Date (Web): November 1, 2016

Copyright © 2016 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acs.jpclett.6b02213

The conservation of chiral symmetry has been used as a fundamental rule to determine polymer packing-conformations in racemic systems. We have illustrated, through the interplay of polarization THz spectroscopy and solid-state density functional theory, that the chiral symmetry is not conserved in a poly(lactic acid) stereocomplex (scPLA) system. poly(L-lactic acid) (PLLA) displays a weaker violation of the 31 screw symmetry than poly(D-lactic acid) (PDLA), and possesses a stronger intramolecular vibrational energy, on average, in the low-frequency gamma-point phonon modes than does PDLA. Polarization THz spectroscopy adds a new dimension to polymer crystallography through which new phenomena are expected to be revealed.